The use of the various devices in medical procedures entail a fair degree of manual dexterity on the part of the physician performing the procedures and frequently require the aid of one or more assistants to successfully complete the procedures. One such procedure is the inflation and deflation of balloon systems such as those employed in angioplasty, vertebroplasty, and sinuplasty with standard inflation devices. Device preparation which involves purging or evacuation of air from the balloon systems can be particularly demanding, commonly requiring the use of both hands of a single operator. Many of the medical procedures performed using balloon systems require the physician to use both hands in order to maneuver, position and hold these medical devices during the inflation or deflation steps, thus presenting the need for a second operator to accomplish procedure.
A number of commercial products are available that attempt to address one or more of the challenges associated with controlling the inflation and deflation of a balloon system. Many of these products are focused on providing precise control over the amount of pressure that is applied to the expandable member of the balloon system, as a large contingent of dilatation procedures require a relatively high amount of pressure in order to properly displace tissue, plaque, bone and the like. For example, many commercial available inflation devices comprise a syringe with a pressure gauge attached, wherein the syringe plunger is free to move longitudinally within the inner bore of the syringe barrel by pulling on a handle provided on the syringe plunger proximal end. The action of retracting the syringe plunger proximally provides a vacuum within the syringe to draw fluid or air into the syringe barrel. Conversely, pushing on the handle of the syringe plunger discharges the fluid or air out of the syringe. In a closed system (e.g. when the inflation device is attached to a balloon catheter) a sealing member (typically attached to the distal end of the syringe plunger) acts as a gasket to prevent fluid or air to leak around the gap between the inner wall of the syringe barrel and the outer surface of the syringe plunger when the syringe plunger is advanced towards the distal end of the inflation device (in order to generate pressure) or retracted proximally (in order to generate vacuum). The sealing member attached at the distal end of the syringe plunger allows the fluid or air within the closed system (the inflation/deflation device and the coupled medical device such as balloon catheter) to be compressed, increasing the internal pressure as the plunger continues to advance distally. The operator can observe the reading on the pressure gauge to ascertain that magnitude of pressure within the system. Another mechanism of inflation comprises a syringe plunger that is threaded, wherein the thread is engaged with an element of the device so that the longitudinal movement in the distal direction within the syringe barrel is effected by rotation of the threaded syringe plunger thus building up pressure within the device. The descriptions of these inflation devices are referenced in U.S. Pat. Nos. 4,743,230, 4,832,692, 5,507,727, and 7,530,970 which have been incorporated herein by reference. Other designs such as the locking syringe described in U.S. Pat. Nos. 5,047,015, 5,057,078, and 5,209,732 (herein incorporated in full by reference) allow for the selection and maintenance of a given inflation pressure.
Another method of simplifying the inflation and/or deflation of a balloon or other expandable member is illustrated in devices that allow for a pre-selected level of negative pressure to be applied and maintained without constant effort on the part of the operator. One example of this type of design is the VacLok® series of syringes available from Merit Medical. These devices comprise a polycarbonate syringe body with a stop pin and a plunger with locking fins that prevents relative motion of the plunger with respect to the syringe body when the fins are engaged with the stop pin. Vacuum is applied and maintained by retracting the syringe plunger to create a desired negative pressure, then rotating the plunger to position one of the locking fins proximal to the stop pin. The interference between the locking fin and the stop pin prevents distal motion of the plunger and the release of negative pressure. These types of designs are taught in U.S. Pat. No. 5,215,536 and are herein incorporated by reference.
Another typical inflation/deflation syringe set up that may be used for inflation and deflation of a medical device such as balloon catheter comprises a small volume syringe (e.g. 1 ml syringe), a large volume syringe (e.g. 10 ml syringe) and a manifold (e.g. 3 way manifold or stopcock) assembled together. The small volume syringe is used to provide high inflation pressures with minimal effort (due to the relatively small syringe plunger cross section), the large volume syringe is used to apply vacuum for deflation as well as serve as a reservoir for the inflation fluid media, and the manifold or stopcock functions to open or close ports enabling communication between the balloon catheter and the desired syringe. The use of the large syringe is needed as the small syringe is not capable of producing the magnitude of vacuum required for timely to deflation of the balloon, nor does it hold a sufficient volume of fluid to compensate for the void volume of the balloon catheter, inflate the balloon to a neutral pressure, and further increase the pressure in the balloon to the desired level. The method of inflation or deflation involves rotating the valve of the manifold or stopcock in order for the balloon catheter to communicate with the inflation syringe or the deflation syringe. For example, a high pressure balloon may be inflated by rotating the valve of the manifold or stopcock to open a flow path between the larger syringe and the balloon catheter. After evacuating the air in the balloon catheter, the larger syringe in depressed to fill the void volume of the balloon catheter and begin inflating the balloon. At this point, the force required to further inflate the balloon exceeds the amount that can be comfortably applied by the operator. The valve of the manifold or stopcock is rotated further to close the flow path between the larger syringe and the balloon catheter and open a flow path between the smaller syringe and the balloon catheter. The operator continues to inflate the balloon to the desired pressure by depressing the smaller syringe. Once the desired pressure has been achieved, the valve of the manifold or stopcock is rotated to close all flow paths between the syringes and the balloon catheter. Deflation of the balloon is achieved by rotating the valve of the manifold or stopcock to open a flow path between the larger syringe and the balloon catheter and retracting the plunger of the larger syringe to generate a negative pressure in the syringe barrel. The negative pressure draws fluid out of the balloon catheter and deflates the balloon. In this set up, it is apparent that there is an added operator burden or difficulty since the operation involves several manipulations of a stopcock or manifold in order for the system to operate correctly.
While these inflation devices have utility, they are not the most efficient and convenient for the physician and medical staff to use in the field due to the need for two hands to successfully operate the devices, the ergonomics and bulk of the current designs, and the number steps needed to prepare and deploy the inflation mechanism.
An inflation and/or deflation device that would simplify the dilation of an expandable member, such as a balloon catheter, that can be successfully operated with one hand would relieve the burden placed on the physician operator and associated staff during often complex medical procedures, and thus potentially presents a labor cost savings.